Situational Awareness (Thursday, 2026-08-06)
Rainfall over the past few days has not raised Potomac River flows significantly. The Middle Atlantic River Forecast Center predicts 0.1 to1.0 inches of rain over the next 3 days.
Special Conditions
The National Park Service has informed us that the annual off-water inspection at Potomac Dam No. 4 in Washington County, MD, will take next week (Tuesday, August 11, 2026). During this time, the hydroelectric operator – Eagle Creek Renewables will be diverting water off of the run-of-river dam crest through their powerhouse turbines. This will cause intra-daily flow fluctuations at the Point of Rocks gage.
Daily flows:
Little Falls gage flow 2026-08-05: 1286 MGD (1990 cfs)
Little Falls gage flow 2026-08-06: 1396 MGD (est., based on recently available real-time data) (2160 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2026-08-05: 1196 MGD (1850 cfs)
Point of Rocks flow 2026-08-06: 1150 MGD (est., based on recently available real-time data) (1780 cfs)
Yesterday's estimated daily flows:
Great Falls estimated flow 2026-08-05: 1286 MGD (1990 cfs)
Note: Estimated flow below Great Falls intake is flow at Little Falls plus Little Falls water supply withdrawal.
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2026-08-05):
Fairfax Water Corbalis withdrawal - Potomac: 101 MGD
WSSC Water Potomac withdrawal: 157 MGD
Washington Aqueduct withdrawal - Great Falls: 138 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 12 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 408 MGD
Total net Potomac withdrawal: 401 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1850 cfs
QPR, obs: 1850 cfs
QPR, WS: 0 cfs
Interstate Commission on the Potomac River Basin